The AR-15/M16 firearms are designed with two takedown assembly pins which join the upper receiver to the lower receiver. The lower receiver houses the trigger mechanism, hammer, bolt catch & release mechanism, safety mechanism, magazine release mechanism, magazine well, and recoil buffer assembly. All of these components are critical for the safe and reliable operation of the firearm.
When the takedown assembly pins are disengaged, the upper and receiver can be separated for storage, transport, inspection, or cleaning. While the upper and lower receivers are separated, the components and internal cavities within the lower receiver are exposed and subject to damage debris. Unprohibited movement of the hammer is also possible in this separated state and can lead to hammer over-travel. This hammer over-travel can damage the lower receiver housing, bolt catch & release mechanism and hammer.
Firearm protective cases and bags do not provide adequate protection of the lower receiver inner components because the components are still exposed to impact. Furthermore, any debris already inside the bag or case may become lodged within the lower receiver. Firearm protective cases and bags encase the entire firearm or the entire lower receiver of the firearm, not just the inner components. Firearm protective cases and bags do not attach directly to the lower receiver and fully cover the exposed parts.